First, isolate the absolute value to one side of the equation, while getting everything else to the other side.

|2x + 1| - 3 = 6
|2x + 1| = 9 {added 3 to each side}

Absolute value means “distance from zero”.
If the absolute value of 2x + 1 = 9, then that means (2x + 1) is 9 away from zero.
There are two numbers that are 9 away from zero......9 and -9. Therefore, 2x + 1 could be equal to 9 or -9.